Automatic telephone dialer systems provide a specified output on the telephone line in response to depressing telephone keys. However, the output provided by the telephone dialer is a function of a country in which that dialer is used. This output varies for a number of different countries. For example, there are sixteen different dialer formats in the world. This, therefore requires a dialer that is to operate in all countries to be of sufficient versatility to accommodate the different dialing formats. At present, this typically requires a mask-change on a particular chip to provide a dedicated chip for the associated country. This is undesirable from a production stand point and it would be much more desirable to provide a universal chip which could be programmed externally.
When designing with universal logic, some type of programmable logic such as a PLA is normally utilized. The PLA can be programmed to provide a fixed logic function or it can be programmed for multiple functions that are addressable. In the fixed function logic array, the programming is done with a mask change such that a given dialer chip is useful for only a single country after fabrication thereof. An addressable array, on the other hand, provides the ability to have multiple functions on a given chip after fabrication thereof. The disadvantage to the addressable array, however, is the requirement for additional pins to accept the address input and the requirement for an address generator. In view of these disadvantages, there exists a need to select from a number of different functional options without significantly increasing the number of pins.